<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    //join 拼接字符串
    const arr=['a', 'b', 'c']
   console.log(arr.join());//a,b,c
   console.log(arr.join(''))//abc
   console.log(arr.join('-'))//a-b-c
   console.log(arr);

  </script>
</body>
</html>